Cholinergic manipulations affect sensory responses but not attentional enhancement in macaque MT

Background Attentional modulation in the visual cortex of primates is characterized by multiplicative changes of sensory responses with changes in the attentional state of the animal. The cholinergic system has been linked to such gain changes in V1. Here, we aim to determine if a similar link exists in macaque area MT. While rhesus monkeys performed a top-down spatial attention task, we locally injected a cholinergic agonist or antagonist and recorded single-cell activity. Results Although we confirmed cholinergic influences on sensory responses, there was no additional cholinergic effect on the attentional gain changes. Neither a muscarinic blockage nor a local increase in acetylcholine led to a significant change in the magnitude of spatial attention effects on firing rates. Conclusions This suggests that the cellular mechanisms of attentional modulation in the extrastriate cortex cannot be directly inferred from those in the primary visual cortex.

Pharmacological evaluation of the hydro-alcoholic extract of Campomanesia phaea fruits in rats

Campomanesia phaea (Myrtaceae), popularly known as cambuci, is one of several species of plants producing comestible fruits, largely used in human nutrition. Despite its consumption and economic potential, limited scientific research is available on the Campomanesia, especially those related to its therapeutic benefits. It is reported by traditional medicine the use of the plant in the treatment of different disorders, such as cardiovascular and nervous system disturbances. So, the aim of this study was to carry out the pharmacological evaluation of the hydro-alcoholic extract (HAE) of Campomanesia fruits in rats by screening consisting of tests: a) neuropharmacological observation, b) test on the cardiovascular system. The HAE, prepared from the extraction of fruits with water/ethanol, was concentrated and freeze-dried. Behavioral responses in rats were investigated in open field test and the cardiovascular actions were investigated by a register of indirect blood pressure and the register of spontaneous beating rate right atrium. The results revealed that HAE induced grooming, hypotension and bradycardia. So, this study identified an action on the central nervous system, represented by grooming, and a cardiovascular activity of Campomanesia. The hypotension, attributed in part to bradycardia, was not related to a cholinergic effect, discarding a possible cholinomimetic action of the plant that could justify both cardiovascular and central actions.

Antiamnestic effect of Phlojodicarpus sibiricus extract in a scopolamine-induced amnesia model

The present study was investigated influence of Phlojodicarpus sibiricus (Steph. ex. Spregel) K.-Pol. extract on memory in scopolamine-induced amnesia in rats using object recognition test. The rats were divided into four groups: the first group consist of rats received purified water; rats of two groups administrated scopolamine in dose 1 mg/kg and purified water intraperitoneally; rats of three and four groups introduced scopolamine and P. sibiricus extract in doses 50 and 100 mg/kg accordingly intraperitoneally. The object recognition test was performed 30 minutes after the administration of scopolamine and the P. sibiricus extract. The results of the studies showed that administration of the P. sibiricus extract in animals at doses of 50 and 100 mg/kg prevented the development of amnesia caused by the administration of scopolamine. The antiamnestic effect of P. sibiricus extract is due to the cholinergic effect of coumarins contained in the plant. (For citation: Gulyaev SM, Taraskin VV, Radnayeva LD, Nikolaev SM. Antiamnestic effect of Phlojodicarpus sibiricus extract in a scopolamine-induced amnesia model. Reviews on Clinical Pharmacology and Drug Therapy. 2017;15(4):53-57. doi: 10.17816/RCF15453-57).